The present invention relates to a tool for thermo-compression-bonding chips, and a chip packaging device having the same.
Conventionally, there has been known various types of tools for thermo-compression-bonding chips used for thermo-compression-bonding, i.e., packaging chips on a substrate such as a liquid crystal substrate. For example, a tool for thermo-compression-bonding chips is disclosed in JP 7-86341 (1995), wherein a ceramic holder is mounted on the lower end of a tool main body, with a ceramic heater and a ceramic presser being mounted on the lower end of the ceramic holder.
However, the above-mentioned tool for thermo-compression-bonding chips has the following drawbacks. Although a selected adhesive is used for integration of the ceramic holder, ceramic heater and ceramic presser into a single piece (fixation of three components), difference of thermal expansion by the unevenness in thickness of applied adhesive layers and/or degradation of the adhesive with time, or heat strain caused by the difference in temperature of components arisen from low heat conductivity of adhesive, all may cause parallelism to vary with time and become prone to be out of specified range. The parallelism (parallelism of its working surface and a substrate or a substrate holding stage) or flatness (flatness of its working surface) of the ceramic presser, both of which is simply referred to as xe2x80x9cparallelismxe2x80x9d hereinafter.
In addition, the tool main body and the ceramic heater is usually bolted together, but this bolting is likely to be loosened by the repetition of heating and cooling, because tool main body and bolts are metallic. Furthermore, heat is transferred to a parallelism adjusting mechanism mounted on the upper end portion of the tool main body. These deteriorates the parallelism of the ceramic presser with ease. Parallelism of the ceramic presser is regarded as a decisive factor, especially in packaging which requires a precision of micron order. If it""s parallelism is constantly confined within a specified range, a chip positional shift or the like will never occurs in packaging, So it is not difficult to execute packaging with a high precision, for example, of several xcexcm or less.
Therefore, while the present inventors proposed a tool for thermo-compression-bonding in which a ceramic holder, a ceramic heater and a ceramic presser are sintered, no consideration was given to minimize a influence of thermal expansion and heat transfer in the tool; therefore in the course of successive packaging operations, it result ed in difficulty in packaging with high precision constantly, because of the thermal strain in the tool components and thermal expansion of them. The present invention has been made in light of such drawbacks and in order to eliminate the fault, and it is an object of the present invention to confine a parallelism of a tool for thermo-compression-bonding chips under influences of thermal expansion and thermal transfer within a specified range constantly.
The present invention adopts the following configurations in order to achieve above mentioned object.
More specifically, according to one aspect of the present invention, a tool for thermo-compression-bonding chips, comprises: a tool main body; a ceramic holder directly mounted on the lower end of the tool main body or mounted on the lower end of a connecting block mounted on the lower end of the tool main body; and a ceramic heater and ceramic presser sintered to the lower end of the ceramic holder, wherein the coefficient of linear expansion of the ceramic holder is approximately equal to those of the ceramic heater and ceramic presser, and the thermal conductivities of the ceramic holder and ceramic presser are greater as the pressure surface side of the ceramic presser as seen from the ceramic heater is approached and are smaller as the attaching surface side of the ceramic holder opposite to the pressure surface side is approached.
According to another aspect of the present invention, a tool for thermo-compression-bonding chips, comprises: a tool main body; a ceramic holder directly mounted on the lower end of the tool main body or mounted on the lower end of a connecting block mounted on the lower end of the tool main body; and a ceramic heater-presser sintered to the lower end of the ceramic holder, wherein the coefficient of linear expansion of the ceramic holder is approximately equal to that of the ceramic heater-presser, and the thermal conductivity of the ceramic holder is smaller as the attaching surface side of the ceramic holder as seen from the ceramic heater-presser is approached.
According to a tool for thermo-compression-bonding chips of the present invention, the configuration is adopted in which heat is difficult to be transferred to the tool main body and the attaching portion of the ceramic holder in a limited space including the ceramic holder, ceramic heater and ceramic heater-presser or the like, thereby enabling elimination of elongation and deviation (deformation) in parallelism caused by thermal expansion of the tool main body having a parallelism adjusting function.
The ceramic holder is formed by sintering so that a thermal conductivity gradually decreases toward the attaching portion of the ceramic holder from the ceramic heater side or ceramic heater-presser side; furthermore, adopts a lamination structure in which laminated constituents adjacent to each other have the same or approximately the same coefficient of linear expansion as each other to thereby enable reduction in temperature difference between laminated constituents adjacent to each other (a heat transfer rate can be decreased toward in a direction of heat transfer not rapidly but gradually); therefore, enabling thermo-deformation of the ceramic heater-presser, ceramic presser, ceramic heater, ceramic holder and tool main body to be suppressed.
Accordingly, with this lamination structure adopted, heat is transferred to a chip pressing side with ease, while being transferred to a tool main body side having the parallelism adjusting function with difficulty, and since coefficients of linear expansion of constituents are the same or approximately the same as each other, a problem caused by heat transfer can be solved; thereby enabling realization of packaging with a high precision.
In a tool for thermo-compression-bonding chips according to the present invention, it is preferable that ceramic plates are laminated in such a manner that thermal conductivities thereof become greater from the ceramic heater side toward the tool tip end side (the pressure surface side of the ceramic presser) and the ceramic plates are the same or approximately the same as each other in coefficient of linear expansion, thereby enabling influences of strains and elongation associated with heat transfer to be eliminated.
In a tool for thermo-compression-bonding chips according to the present invention, it is preferable that a heat generating section of the ceramic heater and the upper end portion of the ceramic presser are fitted into or sintered to an attaching recess formed on the lower end surface of the ceramic holder, thereby enabling firm bonding without causing a positional shift to be realized.
It is preferable that a tool for thermo-compression-bonding chips has an air-suction passage passing therethrough and air is sucked through the air-suction passage in a direction from the ceramic presser to the tool main body, thereby enabling suction holding of a chip on a chip-suction hole.
It is preferable that the ceramic holder, ceramic heater, ceramic presser or ceramic heater-presser is made of oxide ceramic or non-oxide ceramic. Though any of oxide ceramic and non-oxide ceramic can be used as a material of the ceramic presser, non-oxide ceramic is preferably used rather than oxide ceramic since a thermal conductivity of non-oxide ceramic can be adjusted.